class_docstr: Base class for a deep forecaster model
docstr: For loss calculation and output prediction
  
  :param batch: a batch contains `(past, past_timestamp, future, future_timestamp)` used for calculating loss and model outputs
  
  :return: calculated loss, deep model outputs and targeted ground truth future
docstr_tok: ["For","loss","calculation","and","output","prediction",":","param","batch",":","a","batch","contains","`","(","past",",","past_timestamp",",","future",",","future_timestamp",")","`","used","for","calculating","loss","and","model","outputs",":","return",":","calculated","loss",",","deep","model","outputs","and","targeted","ground","truth","future"]
code: def _get_batch_model_loss_and_outputs(self, batch):
      """
      For loss calculation and output prediction
  
      :param batch: a batch contains `(past, past_timestamp, future, future_timestamp)` used for calculating loss and model outputs
  
      :return: calculated loss, deep model outputs and targeted ground truth future
      """
      past, past_timestamp, future, future_timestamp = batch
      model_output = self.deep_model(
          past, past_timestamp, future_timestamp
      )
  
      if future is None:
          return None, model_output, None
  
      if self.target_seq_index is not None:
          future = future[
              :, :, self.target_seq_index : self.target_seq_index + 1
          ]
  
      loss = self.loss_fn(model_output, future)
      return loss, model_output, future
  
imports: import copy
  import logging
  import numpy
  import pandas
  from scipy.stats import norm
  from typing import List, Optional, Tuple, Union
  from merlion.models.deep_base import DeepConfig, DeepModelBase
  from merlion.models.forecast.base import ForecasterBase, ForecasterConfig
  from merlion.models.utils.rolling_window_dataset import RollingWindowDataset
  from merlion.models.utils.time_features import get_time_features
  from merlion.models.utils.early_stopping import EarlyStopping
  from merlion.transform.base import TransformBase, Identity
  from merlion.transform.factory import TransformFactory
  from merlion.utils.misc import initializer, ProgressBar
  from merlion.utils.time_series import to_pd_datetime, to_timestamp, TimeSeries, AggregationPolicy, MissingValuePolicy
label_desc: Use image node_id 6 for calling the DeepForecaster obj's underlying member method code with example usage: obj._get_batch_model_loss_and_outputs(batch) and returns: loss,  model_output,  future, None,  model_output,  None